I'd say it would be more difficult to verify the results are legitimate as they are provided by text message. Where as the one you have to pay for you get a proper report. 

I will happily pay the $150 if NZ reopen the bubble to QLD before our planned trip next week. It's a small price to pay for the luxury of still getting to travel in a pandemic when most of our country is still unvaccinated. I doubt Australia will introduce it in the reverse while NZ has no cases.